I have
a Raspberry Pi 3
and I wanted to install Debian on it. I know about
Debian derivatives for the Raspberry Pi, such as
Raspbian, but what I don't like about them is that I
have to use a special APT repository, and have to trust images generated by
these people. I already trust Debian, so why not install Debian on my Raspberry
Pi as well?

Debian has a wiki page about the
Raspberry Pi 3, but it looked pretty experimental. I tried it out, and I'm happy
to report that I got it to work: generating the image myself, booting it up, and
using the resulting system.

To generate the image, I just followed the instructions
here.
I fell into some traps, but @stapelberg just
accepted my pull request
to document them, so you can just follow the instructions and hopefully they
should work.

Once the image is successfully generated in raspi3.img, you can simply write
it to the SD card as explained in the
instructions.
For the last step, if your local network doesn't resolve the rpi3 hostname
(mine didn't), you can simply use nmap to find its IP.
Of course, don't do this if the administrator of your local network could
be worried about a network scan, and adapt it to your IP range:

sudo nmap -p0 192.168.0.1-255

Then you can use the system. What I didn't test:

HDMI: there was no HDMI signal (i.e., no video display), I don't know whether
this is a known limitation or a bug, and whether the system can be made to
use the video. I didn't need it, so I didn't investigate.
Testing again, there seems to be a video signal after all: you can see the TTY
prompt. However, while booting, there is no information displayed about what
happens during the boot process, so you can't hope to debug anything from the
display if booting fails.

Bluetooth and Wifi: there are comments about it
here, but I didn't investigate
either.

Reading the CPU temperature: this does not work currently, I get an error when
trying to cat /sys/devices/virtual/thermal/thermal_zone0/temp, but it
seems that a
patch was checked in so it
should work eventually.

Running stress -c 4 -i 10 -m 2 -d 10 --timeout 300, which worked OK.

Running cryptsetup. The results of cryptsetup benchmark are below. They
are not great (probably due to the lack of hardware crypto support on the
Raspberry
Pi?).
They probably mean that the CPU will be the bottleneck when reading/writing
to an encrypted hard drive.

I just noticed that
there are some default iptables rules (v4, v6)
which prevent remote SSH connections.
Hence, if you want to connect to your Raspberry Pi remotely, once you have made
sure that it is secure to do so (in particular, changed the default password),
you can issue:

sudo iptables -D INPUT 6
sudo ip6tables -D INPUT 4

You should also update /etc/iptables/rules.v4 and /etc/iptables/rules.v6
accordingly (remove the line with REJECT in each file).